Signaling system for railroads



Nov. 8, 1938. o. s. FIELD SIGNALING SYSTEM FOR RAILROADS F iled Sept. 26, 1953 INVENTOR, flfi. 9%,

BY M

fi ATTORN EY a 50 track section including a source of energy E contemplated that this alternator A may be driven 50 Patented Nov. s, 1938 I I 2,135,496

,UNITED STATES PATENT OFFICE SIGNALING SYSTEM FOR RAILROADS Oscar S. Field, Rochester, N. Y., assignor to Gen eral Railway Signal Company, Rochester, N. Y.

Application September 26, 1933, Serial No. 691,026

1 Claim. (Cl. 246-34) This invention relates to signaling systems for applications emp oy ng no -C rails railroads, and more particularly to means by ad ey ay b auxiliary insulated Which a train, the axles of which are electrically ductors suitably supported along the trackway.

insulated from the running rail, can manifest The railway car C is p ovi ed W h tWO Pairs its presence in a particular section of track in of shunt shoes or brushes, RS and RS bearing 5 such asystem. on the right hand rail 3, and LS and LS The conventional steam railway train effects a earing on the left hand rail 2. These shunt dependable electrical shunt upon a railway sig- Shoes or brushes are insulated from each other naling track circuit including the steel rails of and from the body of the car C, and the car- '10 such a track by the various steel wheels and axles r ied pp r tus associated with hese rail Which are held in good current conducting conshunting shoes includes a closed core electrical tact with such rails by the comparatively great choke CH and a powe pp transformer weight of the cars. However, certain railway unt indi at l ys R a IL are a s s cars having non-conducting wheels or running ciated with the rear shunt shoes and are conl5 on non-conducting rails or treads cannot maninected into the shunting means by the associl5 fest their presence in the various sections of ated transformers RT and LT and an associated track by effecting a shunt on such arailway full wave rectifierFR and FL. signaling track circuit. The above described apparatus at the rear of In view of the above and other considerations, the C associated With the Shunt Shoes RS1,

it is proposed in accordance with the present in- RS LS and LS is duplicated at the forward 20 vention to provide on arailway car ameans other end of the car and is connected in an identical than the conventional wheels and axles for effecmanner to the similar shunt shoes or brushes tively shunting the metallic car carrying rails, of S RS LS and. LS*- Fo the p rpo e o a railway signaling track circuit, and if the car p ying t e Present disclOSllIe, the forward carrying rails or treads are not of a conducting apparatus will be considered to be identical to the 25 material, it is further proposed to provide auxilrear apparatus and consequently like reference iary conductors along the trackway which 00- characters have been assigned thereto with disoperate with the above mentioned shunting tinctive exponents. It may be here mentioned means. It is also proposed to superimpose carthat the duplicate apparatus located on the forcarried energy upon such shunting means to Ward and. rear ends of the car has been shown 30 thereby check the integrity and the sufficiency of both for the purpose of providing a more reliable such shunt according to the resistance offered to Shunt While he ear occupies an intermediate the flow of such car-carried current, and it is position in the'track section as well as for retainfurther proposed to superimpose such energy in ing such shunt while the caris standing or pass- 7 a manner which does not interfere with the ing over the insulated joints between two track 35 sensitivity of a conventionally arranged track cirsections, which insulated joints may be staggered cuit. or spaced longitudinally such a distance that the Other objects, purposes and characteristic right hand shunt shoes associated with only one features of the present invention will apear as of the two shunting means shown bears on a con- 40 the description thereof progresses, during which, ductor of one track section and left hand shoes 40 references will be made to the accompanying associated with the same shunting means bears single figure of drawing which shows in a diaon the opposite conductor of the adjacent track grammatic and conventional manner a railway section thereby shunting neither of the adjacent signaling track circuit and a car-carried shuntsections if two sp duplicate shunting means ing means therefor arranged in accordance with were not provided. 45 the present invention. An alternator A is provided on the car C for Referring to the drawing, a railway car is diacontinuously S pp y a Suitable frequency of grammatically shown by a dotted figure C as alternating current to both the rear transformer occupying a conventionally arranged insulated T and the forward transformer T It is connected across one end of the parallel rails or conby any suitable means such as the means emductors 2 and 3 with a conventional track relay ployed for propelling the car C. TR connected across the other ends. These con- ,It is believed now that the usefulness and the ductors 2 and 3 may be the car-carrying rails various inter-related functions of the device and if such are metallic or current conducting, or in the circuits of this specific embodiment of the 55 rail 3 through the shunt shoe RS present invention will be more readily understood by further description being given from th standpoint of operation.

The track section shown in the accompanying drawing is of the conventional closed circuit type which obviously maintains the relay TR energized when the section of the rails 2 and 3 included therein is not occupied by the car C, but as shown in the accompanying drawing, the energy from the source E is shunted through the various multiple paths completed by the carcarried shunt shoes to effect the dropping of the armature of relay TR. For example, one path for the shunted current may be traced from the rail 2 through the shunt shoes LS through the low resistance primary 4 of the transformer LT, wire 5, through the low resistance secondary winding 6 of transformer T, through a second low resistance secondary winding 8 of the transformer T, through the low resistance winding 9 of transformer RT, wire In and to the opposite The shunt shoes LS and RS also furnish a shunt pathfor the direct current from the source of energy E which may be traced from the rail 2 through the shunt shoe LS wire ll, through the low resistance winding l2 of the closed core choke CH, Wires l3 and I4, through a second low resistance winding l5 on the choke CH, wire l6 and to the opposite rail 3 through the shunt shoe RS The secondary windings of the transformer T andthe primary windings of transformers LT and RT are to be of comparatively heavy wire as well as their interconnecting leads in order to afford a low resistance path for this shunt circuit, and likewise the coils l2 and I5 of the choke CH are to be of Very low resistance and to have low resistance interconnecting wires for the same reason. The source of energy E for the track circuit is preferably of a type such as a storage battery for supplying direct current to the rails 2 and 3 in order that theshunt paths including the windings of the various transformers and the windings of the choke CH will impede the flow of such current only due to their resistance which is very small as previously stated, or in other words, the inductance or capacitance of these shunt circuits will in no way impede the flow of continuous current from the track circuit battery E.

The previously traced shunt paths effected by the shunt shoes LS LS RS and RS are obviously in multiple with similar paths through the apparatus provided at the forward end of the car C, or effected by the shunt cshoes LS LS RS and RS but because of their similarity it is not considered necessary to trace the circuits in detail.

The alternating current supplied to the primary of transformer T is induced into the secondary windings 6 and 8 for the purpose of checking the integrity of the contact between the rear shunt shoes and the rails 2 and 3. The circuit for this alternating current induced in a. secondary winding 8 of transformer T may be traced from the upper terminal of winding 8, wires 1 and I4, through winding N3 of the choke CH, wire I6, shunt shoe RS through rail 3, shunt shoe RS wire l0 and through the primary winding 9 of transformer RT to the opposite terminal of the secondary winding 8. The alternating current thus flowing through the primary of transformer RT induces a current in a secondary winding 24 which is changed to direct current by the full wave rectifier FR to maintain the direct current circuit may be traced from the upper terminal of the secondary winding 6, wires 1 and I3, winding l2 of the choke CH wire ll, shunt shoe LS through the rail 2, shunt shoe LS primary winding 4 of transformer LT and back to the opposite terminal of the secondary winding 6 by wire 5. In like manner, the alternating current flowing in the above circuit energizes the relay IL by the transformer LT and the full wave rectifier FL to energize lamp L at front contact 20 and thereby indicate the sufficiency of the contact between the left hand shunt shoes and. the rail 2.

The secondaries of transformers T and T are so arranged that the upper terminals of the secondary windings 6 and l 8 and the lower terminals of the secondary windings 8 and [9 are all of the same instantaneous polarity, or in trans:- former T, the windings 6 and 8 being relatively oppositely arranged, it is obvious that current a will flow in wires l3 and M in the same instantaneous direction. Also, the windings l2 and i5 of the choke CH are so arranged that equal and opposite instantaneous values of flux are produced thereby in the closed core of the choke CH. These equal and opposite values of flux obviously result in a negligible flow of flux within the core of the choke CH thereby producing a negligible amount of reactance to the flow of alternating current inthe windings l2 and Hi.

In a similar manner, the integrity of the contact between the shunt shoes of the forward duplicate shunting means and their associated conductors is checked by alternating current from 1 the associated transformer T or a secondary winding IQ of the transformer T normally causes current to flow through the shunt shoes RS and BS in series to maintain the relay 1R energized thereby lightinglthe associated indicating light R Also, current is supplied to the left hand forward shunt, shoes LS and LS in series by a secondary winding l8 of the transformer T and in a similar manner, is effective to normally energize the relay 1L and indicate the sufficiency of the contact of these shunt shoes by energizing the indicating light L 7 It will nowbe evident that if some abnormal condition increases the resistance between any pair of shunt shoes and the associated rail above a value which is predetermined for effecting a reliable shunt upon the track relay TR, the value of the alternating current flowing in series with such a pair of shunt shoes will be sufliciently reduced to effect the dropping of the associated indicating relay, thereby indicating Such an abnormal condition by extinguishing the indicating light controlled thereby. In addition to this releasing of the relay associated with the 'defec tive contact shoe, the reduction of current in the choke winding in series with the defective shunt shoe will allow flux produced by the opposing choke winding to flow within the core of the choke and thereby produce an impedance in the opposite checking circuit which sufliciently reduces the alternating current therein to also release ,the indicating relay associated with the opposite shunt shoes. For example, the failure of either shunt shoe RS or'RS obviously reduces the checking current to release relay- IR, but this reduction of current in choke winding l unbalances the flux in the core of. the choke CH and allows its winding I2 to act as an impedance which reduces the current flowing through the shunt shoes LS and LS to a point which also releases relay IL and energizes the indicating light L.

.In regard to the function of the response of both indicating means to the failure of one side of the shunting means only, it is contemplated that a single indicating means may suffice for each of the duplicated shunting arrangements. In other words, a single indicating light may be jointly controlled by, both relays or the complete apparatus associated with one indicator such as L may be omitted with a suitable impedance inserted in place of the transformer LT.

As previously described, the normal fiow of alternating current through the coils of the choke CH produces opposing flux to result in a negligi- -ble impedance, but when the shunting means is duplicated for the front and rear of the car, a valuable function of these chokes is to prevent the flow of alternating current from one of the duplicated shunting means to the other in case of a failure of one or more of the shunt shoes to effect a low resistance contact with its rail. Or that is, if the chokes CH and CH were not provided, sufiicient current might obtain during the failure of a shunt shoe due to alternating current flowing between the duplicate shunting means to falsely indicate a shunt across the rails.

For example, in the event of the failure of either shunt shoe RS or LS or both, an abnormal path for the car-carried alternating current may then beformed from the upper terminal of the transformer secondary 8, wire I and i3, choke winding l2, wire I, shunt shoes LS rail 2, shunt shoe LS primary winding 39 of transformer LT wire 29, transformer secondary l8, wires 24 and 25, choke winding 26, wire 2?, shunt shoe RS rail 3, shunt shoe RS wire Iii, primary winding 9 to transformer RT and back to the iower terminal of secondary winding 8. Inasmuch as the upper terminal of transformer secondary 8 is of a relatively opposite instantaneous polarity to the upper terminal of transformer secondary 18, it will be obvious that the voltage thereof will be additive, or each tending to cause current to flow in the same instantaneous direction in the above traced abnormal circuit.

However, the closed core chokes CH and CH function in the above traced abnormal circuit to impede the flow of alternating current to an extent that suificient current is not supplied by transformer RT to hold up relay IR, in case shunt shoe RS has failed and likewise sufficient current is not supplied by transformer LT to relay IL in case shunt shoe LS has failed. In other words the failure of the shunt shoe RS obviously deenergizes winding it of the choke CH which allows flux produced by the abnormal current'in winding I2 to flow within the core of the choke CH and thereby limit the flow of alternating current due to the impedance of the choke winding I? to a value which will not maintain either relay IL energized by its normal circuit or relay IR energized over the above abnormal circuit. In a very similar manner the failure of the shunt shoe LS will de-energiz e winding 22 of choke CH and allow the impedance of winding 26 to limit the flow of alternating current to a value effecting the release of both relays IL and IE Likewise, in case of the failure of either shunt shoe LS or RS or both the choke windings l5 and 22 function in the same manner to limit the flow of alternating current in a similar abnormal circuit thus formed. It will be obvious also that in case of the failure of either shunt shoes RS LS RS or LS an abnormal circuit cannot be formed which will include the associated indicat ing transformers and consequently such a failure will be indicated directly.

A car-carried means for effecting the shunting of a direct current track circuit has thus been provided in which provision has been made for checking the integrity of the contact between the car and the trackway conductors or rails in order that an indication may always be obtained of the sufficiency of the car-carried means to shunt such a direct current track circuit. Attention is particularly directed to the means by which the sufficiency of the contact between the car and the trackway conductors is checked, which comprises a means for superimposing a car-carried source of alternating current upon the shunt circuit in a manner to check the integrity of the contact between the car and the conductors and yet which does not in any way efiect the sensitivity of the conventional track circuit. In other words, the present invention has disclosed a means whereby the current employed for checking the integrity of the shunt is permitted to flow through brushes or shunt shoes in series which bear upon one of the track circuit conductors only instead of applying such car-carried energy in multiple with the source of energy for the track circuit, in which latter case it is obvious that a pulsating current would be produced in the track relay which would materially reduce its sensitivity.

In addition to the feature of checking the sufficiency of the contact between the car and the trackway conductors in accordance with the amount of car-carried current flowing between the car and the trackway conductors, this flow of alternating current has the further advantage of breaking down a high resistance film which is found to ordinarily exist between these brushes and the trackway conductors, and it is contemplated that this breaking down of such film will materially decrease the resistance of the shunt circuit to the flow of the direct current track circuit energy.

In the embodiment shown, the indicating relays are employed to control an indicating light which gives a visible indication concerning the integrity of the associated shunt shoes, but it is obvious that these relays may be arranged to give any desirable indication either visible or audible, and it is further contemplated that such relays may be employed to control the application of an auxiliary shunting means. An auxiliary shunting means which the above mentioned indicating relays may control is fully shown and described in the application of W. K. Howe, Ser. No. 645.013. filed November 30, 1933.

It is also to be understood that in the disclosure of the present invention the shunting apparatus has been duplicated at the forward and rear ends of the car for the various purposes described. but

it is contemplated that this duplication may be present invention except as limited by the appended claim.

Having thus described my invention, what I claim is:

In combination with a railway vehicle out of electrical contact with its metallic running rails, two spaced pairs of insulated conductors carried by the vehicle and in contact'with one rail, two other spaced pairs of insulated conductors carried by the vehicle and in contact with the other rail, means causing rail resistance break-down alternating current to flow along a track rail from one to the other of the two conductors of each of the four pairs of conductors in a given direction at any given instant, means interconnecting like potential points of each of the two pairs contacting with the one rail, each to an opposite pair of the two pairs contacting with the other rail, thus constituting two spaced interconnected pairs, an electrical choke for each of the two interconnected pairs, each choke comprising a core, two Windings on the core and each connected in series with two conductors constituting a pair, the windings being positioned on the core to produce opposing magnetomotive forces when they are traversed by the alternating current flowing in said given direction, and means for indicating the flow of current in each pair of conductors.

OSCAR S. FIELD. 

